hello, i would need some help from anyone who can give some.

This is the problem: i have the installer app on my iphone, but i don't think i have summerboard (to scroll) so now that i've installed enough apps to get the screen full, my installe app is not visible anymore!!!

So basically i need help to get my installer app icon to be visible again so then i can install the summerboard to scroll and get more apps, can anyone help please???